To answer this question, the first thing you need to know is that from the start, Moll made it clear that she would do anything to escape poverty. From a series of marriages to a life of crime, Moll does what it takes to live the life of a "gentlewoman".

The end of the story is somewhat surprising, because Moll, together with her favorite husband, Jemy, end up repenting for all the bad things they have done. They eventually return to England from America, where Moll had initially been sent as a prisoner and where she and Jemy had acquired significant wealth the honest way, by means of good old-fashioned hard work.

I would argue that one of the prevalent themes of this book is the pursuit of comfort. It is comfort and luxury, ultimately, that Moll is after through each of her marriages and every criminal exploit. The fact that she ends up with a comfortable life back home in England therefore represents the fulfillment of her goal, even if this occurs in a way different to the one she would once have imagined.

From relying on her looks to get ahead in her youth to embarking on a life of crime which, according to Moll, are so heinous that she could never reveal her true identity, this book is about a woman determined to live a comfortable life—and the ending shows us that she has achieved exactly that.